Teletype apparatus



A ril 25, 1939.

J. W. ADAMS ET AL TELETYPE APPARATUS Filed April 10, 1957 INVENTOR5 R @7726 W14dama ZZmEert .5. Carnival! ATTORN 5Y5 Patented Apr. 25, 1939 UNITED. STATES TELETYPE APPARATUS James W. Adams, Fostoria, and Robert L. Cornwell, Risingsun, Ohio Application April 10, 1937, Serial No. 136,218

3 Claims.

The object of the invention is to provide a-combined radio transmitter and receiver and associated mechanism, whereby the operation of teletype apparatus may be efiected by the employ- 5 ment of radio waves for the transmission of signals as distinguished from the conventionally employed wire carried signals; to provide an appliance of the kind indicated which will be just as effective in use as the transmission wire actuated apparatus but which at the same time will require but a minimum of space; to provide, in an appliance of the kind indicated, means for setting the teletype actuating motor in operation automatically either as a result of the beginning of the transmitting operation or of the receiving operation; and generally to provide a teletype actuating appliance which is of comparatively simple form and susceptible of cheap manufacture.

With this object in view, the invention consists in a construction and combination of parts of which a preferred embodiment is illustrated in the accompanying drawing to which embodiment, however, the invention is not to be restricted further than restrictions are imposed by the appended claims.

In the drawing:

Figure 1 is a diagrammatic view illustrating the apparatus employed in the invention.

Figure 2 is a further detail diagrammatic view of the shift-over switch.

The complete appliance consists of four apparatus, as indicated at A, B, C and D, that at A being a combined radio transmitting and receiving apparatus, or transceiver, that at B being a multiple switch of the double throw type which is set in one position for the receiving operation and in another position for the transmitting operation, that at being the conventional teletype apparatus, and that at D the power plant for 40 energizing both the transceiver and the teletype actuating apparatus.

The transceiver unit A is of the ultra-short wave or micro wave design, since such a transceiver requires but very few parts, functions with 45 small radio tubes, requires but small space for installation and can be operated at a minimum current consumption.

The antenna system consists of a pick-up coil ID, or its equivalent, and an attendant radiating system H. The radio tube l2 which functions as an oscillator during the transmitting operation and as a detector during the receiving operation is of the ultra high frequency type. Its plate and grid are bridged with a variable condenser 55 I3 and a fixed condenser 14. The small radio frequency choke coils l5 and I6 are connected respectively to the grid and plate of the tube, the former having its opposite end grounded through the resistances l1 and i8 and the latter having its opposite end connected with the movable arm of a switch I9 which in itself is a single pole double throw switch but which is in reality an element of the switch mechanism B. The movable element of the switch is is engageable either with the T or R contacts. A by-pass condenser 2|] is placed between the movable element of the switch [9- and the ground.

A switch 2| which is also an element of the switch mechanism B and is identical in construction with the switch 19 has its movable element connected between the resistances I! and I8 and its T contact grounded, the R. contact being idle.

The tube I2 is of the heater type, as is also the tube 22, the heating filaments thereof being energized from the power pack D through the conductors 23 in which are interposed the radio frequency choke coils 24. The tube 22 is both an amplifier and rectifier tube and is coupled to the tube l2 through an audio frequency transformer 25, whose secondary is connected to the grid of the tube and to ground and whose primary is connected to the R contact of the switch l9 and to the positive terminal of the plate energizing source through the switch mechanism B as is hereinafter explained.

The cathode of the tube 22 is connected with the movable element of a switch 26, identical in form with the switches l9 and 2| and also an element of the switch mechanism B for synchronous operation with the other switches. The T contact of the switch 28 is connected with ground through a fixed resistor 21, while the R contact is connected with ground through a radio frequency choke coil 23 and a biasing resistor 29 which is in series with the choke coil but which is by-passed with a fixed condenser 30.

A switch 3| identical in form with the switches l9, 2| and 26 and like them an element of the switch mechanism B has its movable element connected with the plate of the tube 22, its T contact idle, or dead, and its R contact connected with the plate supply and with the T contact of the switch I9. Plate energizing current for both the tubes l2 and 22 is fed through a variable resistor 32.

The unit C employed as an element of the invention is the conventional teletype apparatus having the selector magnets 33, the contacts 34 and 35 of which the contacts 34a and 35a are normally closed while the other contacts are normally open, and the conventional actuating motor 36. The operation of the motor is controlled through a double-pole double-throw switch 31 of which the blades 31a and 311) are insulated from each other but operatively connected to move in synchronism to engage respectively the contacts 38 and 39 or the contacts 40 and 4|. The switch is automatically moved into engagement with the contacts 40 and 4| when the magnet 42 is energized and in practice a latch will be provided for maintaining this position after movement in response to magnet energization. A manual release in the form of a pull knob 43 is provided to efiect blade engagement with the contacts 38 and 39, the latter and contact 40, being dead or idle contacts.

The unit D consists of the power plant composed of a transformer 44 whose secondary 45 is center-tapped and grounded at the tap but whose terminals connect with the conductors 23, so that current for the heater filament of the tubes l2 and 22 is provided. The secondary 46 has its terminals connected with the plates of a full wave rectifier 41 whose filament is energized by the secondary 48. The center-tap of the secondary 46 constitutes the plate return. The plate current is filtered in the usual manner by the filter chokes 49 and a tapped resistor 50 constitutes the means for taking oif the desired plate energizing and relay voltages. The primary is controlled by a hand switch 52 which likewise controls the motor 36 through the switch 31. That is, the switch 52 must be closed before the switch 31 can in any way function to control operation of the motor 36.

The unit B constitutes the shift-over switch for the apparatus and in addition to the switches |9, 2|, 26 and 3| includes the switches 53, 54, 55, 56, 51, 58, 59, 60, 6| and 62. All of the switches are connected for synchronous operation and are of the single-pole double-throw type, having contacts identified respectively as T and R to indicate the transmitting and receiving positions of the switches.

In addition to the switches I9, 2|, 26, 3| and 53 to 62 inclusive, the unit B includes a switch 63 of the double-pole double-throw type, the blade 64 moving into engagement with either the contact 55 or 66 and the blade 61 engaging either the contact 68 or 69. The contacts 66 and 6B 'are dead or idle contacts and the blades are yieldingly held in engagement with these contacts by means of a tension spring 10. The blades are engaged with the contacts 65 and 69 when the relay 1| is energized and it is energized intermittently in the operation of the apparatus so that the switch blade 64 will act as an interrupter of the continuous waves employed in the operation of the apparatus.

Idle, the parts are in the positions indicated in the drawing, the shift-over switch mechanism B being preferably in the receiving position wherein the movable elements engage the cooperating contacts B. When the switch 52 is closed, a potential is applied to the blade 31b of the switch 31 over the conductor 12 and to the contact 4| over the conductor 13 through the motor 36. Thus when the blade 31b engages the contact 4|, the motor 36 will be energized. But this operation will not take place until the blade is moved by reason of the magnet or relay 42 being energized. Assuming that the apparatus is to be used to transmit teletype signals, the shift-over switch mechanism B is adjusted to engage the movable elements of the various switches with the T contacts. In the transceiver, this will result in cutting the tube 212 out of circuit by interrupting its plate circuit because of the movable element of the switch 3| engaging the dead contact T thereof. But the plate of the tube 2 will have B current applied direct thereto from the power pack D over the conductor 14, the conductor 15, the T contact of the switch 66, the blade of said switch 66, the conductor 16, in which is included a radio frequency choke coil 11, the

variable resistor 32, the conductor 18, the conductor 19, the conductor 80, the radio frequency choke coil l6, the plate of the tube 2, the cathode of the tube, the ground connection thereof, the radio frequency choke coil 8|, the conductor 82, the blade and T contacts of switch 59, the conductor 83, the switch blade 64, the contact 65, the conductor 84, the conductor 85, the blade and T contacts of the switch 56, the conductor 86 back to the center-tap of the secondary 46 of the transformer 44. But this circuit will be interrupted at the points 6465, and will only be established when the relay 1| is energized.

The contacts 34 and 34a and 35 and 35a are the actual controlling means of the carrier wave or signal being transmitted and the contacts 34a and 35a are normally engaged until one of the other contacts is depressed. Thus a circuit is established on the relay 1| to engage the blade 64 with contact 65, current flowing over the conductor 14 to the T contact of the switch 54, thence over the movable element of the latter, the conductor 81, the relay 1|, the conductor 88, the T contact of the switch 51, the conductor 89, the selector magnets 33, the contact 34a, contact 35a, the conductor 90, the T contact of the switch 55, the blade of said switch and the conductor 86 back to the source.

But it is necessary in the operation of the teletype apparatus, that the motor 36 be put in operation and this is accomplished when the relay 1| is energized, for then the blade 61 is engaged with the contact 69, which places the relay or magnet 42 in circuit, current flowing over the conductor 9| from the high potential tap in the power pack D to the switch blade 31a which, being engaged with the contact 38, permits passage of current from that contact to the coil 42, thence the contact 69, the blade 61, the conductor 92, the switch 62, the T and R contacts of the same being bridged, the conductor 86 back to the source. But when the relay 42 is energized, the switch 31 is actuated and the blades 31a and 311) are engaged with the contacts 4|] and 4| respectively where they are held, as hereinbefore described. The circuit on the relay 42 is then broken but the circuit of the motor 36 is closed, current flowing from the line over the conductor 12 to the switch 311), the contact 4|, the motor 36 and the conductor 13 back to the supply line. The motor will thus continue to operate until it is manually cut out of circuit by throwing the switch 31 back to its former position through the instrumentality of the pull knob 43.

The switches 2| and 26, being in the T positions, the cathode of the tube 22 is connected with ground through the resistor 21 and the radio frequency choke coil I5 to the ground through the resistor |1. But the coils l5 and I6 are coupled so that the plate and grid circuits are coupled to cause the tube to oscillate and as the contacts 34 are actuated for the desired teletype signal, the continuous wave transmitted is interrupted by the opening and closing of the switch 63. But despite the fact that the blade element 61 of this switch controls the relay 42, the latter is likewise controlled by the blade element 31a of the switch 31, which blade element remains disengaged from its contact 38 after the initial operation of the switch.

On cessation of the transmitting operation, the entire apparatus may be cut out of circuit by opening the switch 52, since this controls not only the power pack D but the motor as well. The opening of the switch 52, however, should be attended with the manual shifting of the switch 31 to engage its two blades with the contacts 38 and 39.

For the receiving operation, the shift-over switch mechanism B is adjusted to engage the blades of the various switches with the R contacts and the switch 52 is then closed. The switch 2! will then ground the coil l5 through the two resistors l1 and [8 while the switch 26 will ground the cathode of the tube 22 through the choke coil 28 and the biasing resistor 29 which is of such a value as to give zero value to the plate current except when a signal is impressed upon the grid of the tube which is not only an amplifier but a rectifier as well. In the receiving position the switch l9 connects the primary of the audio transformer 25 in the plate circuit of the tube !2, while the switch 3!, in such receiving position, connects the plate of the tube 22 in circuit, plate current fiowing over the conductor 18 to the plate of the tube 22 and over the conductors 93 and to the plate of the tube 12, the primary of the transformer being included in the conductor 93.

In the receiving position, plate current reaches the variable resistor 32 through the relay H and switch 58, flowing over the conductor 15 to the blade of the switch 58, thence to the R contact, thence to the conductor 81, thence the relay H, thence the R contact of the switch 60, thence the blade of the switch and the conductor 16 and choke coil 11. The plate current return is from the cathodes of the two tubes to the indicated ground connections of unit A, thence over the choke coil Bl, the conductor 82, the R. contact of the switch 59, and the conductor 86 back to the source. When a signal is impressed on the grid and its potential changed thereby, plate current flows in the tube 22 whereas it was previously at zero. But upon plate current flowing, the relay H is energized and the switch 63 operated as before described, the blade 61 closing the circuit on the relay 42 and the motor 36 being put in operation in consequence.

In the receiving operation, the tube I2 functions as a detector, while the tube 22 functions not only as an amplifier but as a rectifier and is biased by the resistor 29 to plate cut-off current, in whose plate circuit the relay H is serially included. Thus when the plate current flows in the tube 22 due to the impressing of a signal on its grid, the relay H will be operated and this in correspondence with the received signal. Since the one set of contact points 34a. and 35a of the teletype apparatus remain closed during the entire period of reception of teletype communication, the relay H will control the energizing and de-energizing of the selector magnets 33 which in turn operate the printing mechanism of the teletype machine.

Since it is necessary for the electric motor 36 to be in operation throughout the period of reception of teletype communications, the arrangement provides for the automatic starting of the motor on the reception of a signal, just as for its automatic starting when the transmitting operating is being performed.

The invention having been described, what is claimed as new and useful is:

1. In a system of radio communication which comprises a teletype apparatus having transmitting contacts, selector magnets and an actuating motor, a transceiver for selectively receiving continuous wave impulses or for generating sustained oscillations, an energizing source for the transceiver, and an energizing circuit for the actuating motor; the improvement which comprises a control switch included in circuit with the motor, manually actuable means connecting the energizing source with the transceiver and the former with the selector magnets and the transmitting contacts of the teletype apparatus to selectively adapt the transceiver and teletype apparatus respectively to the transmitting and sending functions and alternatively to adapt the two to the receiving and printing functions respectively, and actuating means for the motor control switch to automatically move it to closed position, the said actuating means being energized from the energizing source for the transceiver, the manually actuable means controlling the switch actuating means in adapting the transceiver to either of its functions.

2. In a system of radio communication which comprises a teletype apparatus having transmitting contacts and selector magnets, a transceiver for selectively receiving continuous wave impulses or for generating sustained oscillations and including an oscillator and a combined amplifier and rectifier; the improvement which comprises a plurality of single-pole double-throw switches synchronized for simultaneous operation and interposed between the energizing source and the transceiver and between the former and the selector magnets and transmitting contacts of the teletype apparatus to selectively adapt the transceiver and teletype apparatus respectively to the transmitting and sending functions or alternatively to adapt them to the receiving and printing functions, certain of said switches being interposed in the plate circuits of the oscillator and amplifier to disconnect the latter from the energizing source during the transmitting function but to connect the same with the energizing source and couple it with the oscillator tube during the receiving function.

3. In a system of radio communication which comprises a teletype apparatus having transmitting contacts and selector magnets, a transceiver for selectively receiving continuous wave impulses or for generating sustained oscillations, and an energizing source for the transceiver; the improvement which comprises a plurality of singlepole double-throw switches synchronized for simultaneous operation and interposed between the energizing source and the transceiver and between the former and the selector magnets and transmitting contacts of the teletype apparatus to selectively adapt the transceiver and teletype apparatus respectively to the transmitting and sending functions or alternatively to adapt them to the receiving and printing functions, an additional switch yieldingly held in open position and interposed between the energizing source and the transceiver, one of the synchronized switches connecting the last said switch directly in the transceiver circuit in one position but not in the other and another of the synchronized switches connecting the first said switch in both the transceiver and. selector magnet circuits in one of its positions only, and automatic means for intermittently closing said switch and controlled either by the transmitting contacts or the received impulses.

JAMES W. ADAMS. ROBERT L. CORNWELL. 

